Storage battery

Abstract

A lead-acid storage battery uses as a current collector an expanded grid produced by processing a belt shaped material formed of lead or lead alloys. Strand of a grid for negative electrodes have a twist. The extent of the negative electrode's grid is larger than that of the positive electrode's grid. Accordingly, degradation of output characteristics in the domain deep in the depth of discharge is prevented and further high rate discharge cycle life characteristics are improved.

What is claimed is:  
     
       1. A storage battery comprising; 
       a positive electrode, a negative electrode and an electrolyte material, wherein  
       said negative electrode has a first grid with a first grid geometry and a first active material provided on said first grid;  
       said positive electrode has a second grid with a second grid geometry and a second active material provided on said second grid; and  
       said first grid includes a plurality of first twisted strands having a first extent of twist  
       said second grid includes a plurality of second twisted strands, having a second extent of twist smaller than said first extent of twist.  
     
     
       2. The storage battery according to claim  1 , wherein said first grid includes an expanded grid. 
     
     
       3. The storage battery according to claim  1 , wherein said first grid includes an expanded grid that is produced by processing a belt shaped material. 
     
     
       4. The storage battery according to claim  1 , wherein said first grid is formed of at least one material selected from the group consisting of lead and lead alloys. 
     
     
       5. A storage battery comprising: 
       a positive electrode, a negative electrode and an electrolyte material, wherein  
       said negative electrode has a first grid with a first grid geometry and a first active material provided on said first grid;  
       said positive electrode has a second grid with a second grid geometry and a second active material provided on said second grid; and  
       said first grid includes a plurality of first twisted strands and a first connecting section for each respective grid strand of said plurality of first twisted strands, said second grid includes a plurality of second strands that are not twisted, and a second connecting section for each respective grid strand of said plurality of second strands.  
     
     
       6. The storage battery according to claim  1 , wherein said second grid is formed of at least one material selected from the group consisting of lead and lead alloys. 
     
     
       7. The storage battery according to claim  1 , wherein said first grid includes an expanded grid produced by a rotary cutting method. 
     
     
       8. The storage battery according to claim  1 , wherein said second grid includes an expanded grid produced by a reciprocating cutting method. 
     
     
       9. A storage battery comprising: 
       a positive electrode, a negative electrode and an electrolyte material, wherein said negative electrode has a first expanded grid and a first active material provided on said first grid;  
       said positive electrode has a second expanded grid and a second active material provided on said second grid;  
       said first and second expanded grids are formed of at least one belt shaped material selected from the group consisting of lead and lead alloys;  
       said first grid includes a plurality of first twisted strands having a first extent of twist;  
       said second grid includes a plurality of second twisted strands having a second extent of twist smaller than said first extent of twist.